feat: task management enhancements (cancelled status, recurrence, timestamps)

- Add 'cancelled' status to TaskStatus type, StatusBadge, TaskCard,
  TaskEditorView, TaskViewerView, TasksListView
- Add RecurrenceEditor component (none / interval / calendar rules)
- TaskEditorView: wire RecurrenceEditor, show started_at/completed_at
  timestamps read-only, include recurrence_rule in save payload
- TaskViewerView: show recurrence summary, timestamps in meta row
- tasks.ts: statusFilter/priorityFilter as arrays, add recurrence_rule
  to updateTask and createTask payloads

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/types/note.ts

@@ -1,4 +1,4 @@
-export type TaskStatus = "todo" | "in_progress" | "done";
+export type TaskStatus = "todo" | "in_progress" | "done" | "cancelled";
 export type TaskPriority = "none" | "low" | "medium" | "high";
 
 export interface Note {
@@ -13,6 +13,10 @@ export interface Note {
   status: TaskStatus | null;
   priority: TaskPriority | null;
   due_date: string | null;
+  started_at: string | null;
+  completed_at: string | null;
+  recurrence_rule: Record<string, unknown> | null;
+  recurrence_next_spawn_at: string | null;
   is_task: boolean;
   created_at: string;
   updated_at: string;